Time-element circuit controller



' May 22, 1923. 1,456,100.

J. EATON TIME ELEMENT CIRCUIT CONTROLLER Filed Jan. 15 1920 Inventof": do n Eaton Hi Attorney.-

Patented May 22, 1923.

UNITED STATES PATENT OFFICE.

JOHN EATON, OF BCHENEOTADY, NEW YORK, ASSIGNOB TO GENERAL ELECTRIC COMPANY, A CORPORATION OF NEW YORK.

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To all concern: Be it known that I Joint Enron, a enhject of the King of Great Britain, residing at Schenectady, in the county of Schee nectady, State of New York, have invented certain new and useful Improvements in Time-Element Circuit Controllers, of which the following is a specification.

My invention relates to time element dcto vices for controlling electric circuits and it provides improved means whereby a definite time interval in the control of an electric circuit is provided. One of the objects of my invention is to provide a time element 315 device which will be simple and positive in action and one which has little likelihood of getting out of adjustment. 4

in carrying my invention into efiect, I provide an e ectric motor, and an electroas magnetic switch which is energized responsively to the motor armature voltage, the arrangement being such that when the motor is connected to a source of supply, the electromagnetic switch will instantly close 2 and thereby efi'ect the closing of the circuit which it is desired shall be maintained closed. When the motor is deenergized, the electromagnetic switch is maintained closed "for a definite interval against its bias to the at open position by reason of the fact that the motor will operate as a generator to main tain the energization of the coil of the electromagnetic switch. When the speed of the motor has dropped to such a, value that the W generated voltage is less than that required to maintain the electromagnetic switch closed, the switch will automatically open the controlled circuit. LA definite time interval will thus be provided between the 441i time at which the motor was disconnected from the source of supply and the time at which the electromagnetic switch opens. in the preferred form of my invention, ll provide the motor with a fiy-wheel so that the motor will have considerable inertia, and by varying the weight of this fly-wheel ll am able to vary the time limit. The time limit may also he obviously varied by varying the excitation of the motor.

all her a better understanding of my inven= tion, reference is had to the accompanying drawing wherein it have illustrated diagrammatically and in simplified form an embodiment of my invention in the control of the shunt field of an electric motor. 5 Referring to the drawin the electric motor, having an armature and a shunt field F which is adapted to be controlled in accordance with my invention, is adapted to be started, stopped and reversed by means including the controller (1. The electromagnetic switches 10 and 11 are provided for connecting the motor armature to the source of supply for operation in one direction and the electromagnetic switches l2 and 13 are provided for connecting the motor armature to the source for operation in the other direction. The electromagnetic switches 14 and 15, having series windings, are the well-known type which are mag- 'netically held open when the current taken by the motor armature is in excess of a predetermined value andv are closed and magnetically held closed when the motor cur-' rent drops to the predetermined value. The switch it is adaged to short circuit the starting resistor rand the switch 15 is adapted to short circuit the start-resistor R The resistor R included in the circuit with the field F is adapted to be controlled by means of the electromagnetic switch or relay id. The winding of this relay is connected across the armature a of an electric motor, the rotating element of which has considerable inertia. In the particular arrangement shown, the rotating element of this armature is given a considerable inertia by the provision of a fiy-wheel 17 connected thereto. This electric motor is provided with a shunt field 7".

As thus constructed and arranged, and with the parts in the position as shown in the drawing, the operation of my invention is as follows: Turning the controller 0 to the right to its operative position energizes the electro-magnetic switches 12 and 13 to connect the motor armature A to the source of supply throu h a circuit includin the resistors R and Simultaneously tilere with the armature a is connected to the 100 source of supply and the winding of the throu h supply, so that the relay 16 will close its contacts and short circuit the resistor R in the motor field F. The starting resistors R and R will be automatically short circuited as the motor increases in speed by means of the series contactors 14 and 15 in a well understood manner, and the motor having the fiy-wheel connected-to its rotating element will also be accelerated to full operatin speed. Assume now that the controller (J is returned through its off position to its other operative position, the contactors 12and 13 will be deenergized and open their contacts and the contactors 10 and 11 will be energized to close their contacts so as to connect the motor armature to the source of supply with the current motor armature reversed for the reverse direction. When C passes through the ofi' posicontactors 12 and 13 are deseries contactors 14 and 15 are ed to reinsertthe starting resis- R in the motor armature circuit. reason the fact that the armature a has considerable inertia effect, it will operate as maintain the energization of of the relay 16, and while the Aer is thrown to its left-hand position, the armature a will be connected to the source oi supply in the same manner as before, will be observed that in passing through the 03 position of the controller, the field F is maintained at full strength since the relay 16 is maintained closed by reason of the generated current of the armature a. If the controller C is now returned to the off osition and left there, the armature A wi 1 be disconnected from the source of supply, but the relay 16 will be maintained closed so as tomaintain full field strength for the shunt field F, for a definite interval determined by the inertia effect of the armature a and the excitation of the field f. After the predetermined interval, the generated voltage of the armature a will have decreased to such a value that the relay 16 will be permitted to open its contacts in accordance with its bias and insert the resistor R in the circuit or the shunt field F. It will be observed that with thisarrangement the excitation of the shunt field F is at full strength at starting and is maintained at full strength when the direction of current in the motor armature A is re versed, but that in case the controller C is returned to the ofi position and left there, the current in the shunt field F will be automatically reduced to prevent over heating after a definite interval of time determined b the inertia effect of the armature a and tlie degree of excitation of'the shunt field f.

the motor controlled thereby, since the amount of work performed by the motor 15 relatively uite small.

In accor ance with the provisions of the patent statutes, I have described the principle of operation of my invention; to other with the apparatus which I now consi er to represent the best embodiment thereof, but I desire to have it understood that the apparatus shown is oniy iliustrative and that the invention may be carried out by other means.

What I ate bv Letters Eaten- 1. A time circuit controii tating element of United States, is: evice comprising a ectric motor lthc roiich has a relatively large inert'a c d by said controller, an electrcmagctrc itch, and connections between. the motor, the winding of said switch and the said controller, whereby the switch winding and motor are simultaneously opcratively energized responsive to the operation of the controller, and the switch is maintained energized responsively to the generated volts e of the motor when the motor and the switch winding are disconnected from the source of supply by the subsequent operation of the controller.

2; The combination in a time element device of an electric motor having a shunt field energized form a source of supply, an electromagnetic switch biased to one position and havin its energizing winding connected across t e motor armature, a circuit external to the motor controlled thereby, and a common connection for the armature of said motor and the winding of said switch whereby energizing the motor armature from the source of supply causes the windin of said switch to be energized to move t e switch to another position against its bias'and disconnecting the motor armature from the source-causes the winding of said switch'to be energized from the motor operating as a generator so as to maintain the switch in said other positionagaind; its bias for an interval of t1me determined by the inertia efi'ect of the rotating element of said motor.

3. The combination in a time clement device of an electric motor, a controller therefor, an electromagnetic switch energized responsively to the voltage drop across the motor armature a circuit external to the motor controlled thereby, and connections new nd desire to secure 1 whereby closing the motor circuit through maintain the controlled circuit closed for a the operation of the controller simultanedefinite time interval after the motor conously energizes the electromagnetic switch to troller is moved to the off position. 10 close the controlled circuit and moving the In witness whereof, I have hereunto set 6 controller to the ofi position causes the elecmy h nd s 13 h day of J anuary 1920.

tromagnetic switch to be energized from the motor operating as generator so as to JOHN EATON. 

